Interaction between Calpain 5, Peroxisome proliferator-activated receptor-gamma and Peroxisome proliferator-activated receptor-delta genes: a polygenic approach to obesity.

CONTEXT: Obesity is a multifactorial disorder, that is, a disease determined by the combined effect of genes and environment. In this context, polygenic approaches are needed. OBJECTIVE: To investigate the possibility of the existence of a crosstalk between the CALPAIN 10 homologue CALPAIN 5 and nuclear receptors of the peroxisome proliferator-activated receptors family. DESIGN: Cross-sectional, genetic association study and gene-gene interaction analysis. SUBJECTS: The study sample comprise 1953 individuals, 725 obese (defined as body mass index > or = 30) and 1228 non obese subjects. RESULTS: In the monogenic analysis, only the peroxisome proliferator-activated receptor delta (PPARD) gene was associated with obesity (OR = 1.43 [1.04-1.97], p = 0.027). In addition, we have found a significant interaction between CAPN5 and PPARD genes (p = 0.038) that reduces the risk for obesity in a 55%. CONCLUSION: Our results suggest that CAPN5 and PPARD gene products may also interact in vivo.